bpftool-prog-profile requires clang to generate BTF for global variables.
When compared with older clang, skip this command. This is achieved by
adding a new feature, clang-bpf-global-var, to tools/build/feature.
Signed-off-by: NSong Liu <songliubraving@fb.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Reviewed-by: NQuentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20200312182332.3953408-2-songliubraving@fb.com